The Australian Electoral Commission (AEC) has announced it is challenging the West Australian Senate result to try to bring about a fresh election.

The AEC lodged a petition with the Court of Disputed Returns this afternoon, seeking an order that the election of six senators in WA be declared void.

Nearly 1,400 votes went missing during a formal recount following the September 7 poll.

In a statement, the AEC said:

Given the closeness of the margins that favoured the final two declared candidates, the petition is based on the premise that the inability to include 1,370 missing ballot papers in the recount of the WA Senate election means that the election was likely to be affected for the purposes of s 362(3) of the Commonwealth Electoral Act 1918.

The recount gave the final two Senate spots to the Greens' Scott Ludlam and the Australian Sports Party's Wayne Dropulich, with Labor's Louise Pratt and the Palmer United Party's (PUP) Dio Wang missing out.